


Let Sleeping Dogs Lie

by samucores



Category: Haikyuu!!
Genre: (not really but just in case), Anal Sex, Bottom Miya Osamu, Brother/Brother Incest, Established Relationship, Explicit Sexual Content, Humiliation, Incest, M/M, Mildly Dubious Consent, Multiple Orgasms, Nipple Play, Overstimulation, Piss Play, Sibling Incest, Somnophilia, Spit As Lube, Top Miya Atsumu, Twincest, Unsanitary, Verbal Humiliation, Watersports
Language: English
Status: Completed
Published: 2021-02-19
Updated: 2021-02-19
Packaged: 2021-03-15 21:34:31
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 2,340
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29565489
Author URL: https://archiveofourown.org/users/samucores/pseuds/samucores
Summary: The dim light of the TV made Osamu’s skin look soft and rosy. His face was relaxed and carefree, much more than usual, and his hair was messy in a truly adorable way. He looked so at ease but, more than that, he looked delicate and vulnerable, like a little doll. Atsumu laced his fingers through Osamu’s hair.The way his shorts rode up his thighs looked enticing. The gentle rise and fall of his chest drew attention to his tits. His lips were glossy, too, wet from a thin line of drool leaking out.“God, what am I gonna do with you?” Atsumu muttered. Whether he knew it or not, Osamu was definitely testing his patience right now, especially since it’d been a bit since they last fooled around.Atsumu comes home late to Osamu asleep on the couch.
Relationships: Miya Atsumu/Miya Osamu
Comments: 6
Kudos: 157
Collections: Miyacest Gift Exchange





	Let Sleeping Dogs Lie

**Author's Note:**

> This is for the miyacest server's valentine's gift exchange!!! My original giftee is no longer involved, so now this gift belongs to the people, to _everyone_ , server members and non alike. A fic for the twincest loving masses. Please, enjoy. The prompt was "somno and/or watersports" and I'd like to think I delivered both in spades.
> 
> Warnings for the people: This is very unsanitary sex with lots of bodily fluids (piss), verbal humiliation, and it could be read as dubious consent but I tried to establish that Osamu and Atsumu have had sex before and know each other well and Osamu's like... a Tsundere. He enjoys it, he just doesn't want to admit that cause its embarrassing or whatever. Also they're third years so it could be read as underage but they're probably 18? Either way, I warned just in case.

Being captain meant a lot of things but, most importantly to Atsumu, it meant he could stay after practice as long as he wanted whenever he wanted. Nobody could tell him no. Before, Kita or their coaches would force him to go home, rest up, and take it easy till tomorrow. Now, he had the keys to the gym and all the time in the world—which meant he didn’t have to answer to anyone but himself. Coming home late became a frequent occurrence, and it was usually dark by the time he got back.

Today wasn’t an exception.

Atsumu shut the door behind himself as he walked inside. He slipped his shoes off at the genkan and tossed his gym bag to the side haphazardly, nearly collapsing as he sat down to catch his breath, completely exhausted. He had a bad habit of overworking himself without realizing.

"Samu!" He half shouted, half whined into the darkness of their home. "Make me some food, 'm hungry!"

There was no response. Atsumu found that odd. Typically, Osamu cooked him dinner as soon as he got back. He was always a bit begrudging about it, sure, but Atsumu didn’t even ask half of the time. Osamu started doing it on his own, completely unprompted.

Atsumu pushed himself off the floor. "Samu?" He tried calling again, stumbling into the living room and looking around. It didn't take him long to realize why Osamu wasn't responding: He was fast asleep on the couch, snoring softly and wearing nothing but his practice shorts. 

The TV was still on, so he must’ve dozed off while watching it, Atsumu figured. He did that a lot these days, but this was the first time he fell asleep before Atsumu got back; he usually held in there until Atsumu started eating, like he was staying up late just to feed him.

Atsumu sighed. He walked over to the couch, planning to wake Osamu up and demand food, but he faltered, hand hovering just above his brother's shoulder. Osamu was—He looked  _ cute. _ Atsumu bit his lip.

The dim light of the TV made Osamu’s skin look soft and rosy. His face was relaxed and carefree, much more than usual, and his hair was messy in a truly adorable way. He looked so at ease but, more than that, he looked delicate and vulnerable, like a little doll. Atsumu laced his fingers through Osamu’s hair. 

The way his shorts rode up his thighs looked enticing. The gentle rise and fall of his chest drew attention to his tits. His lips were glossy, too, wet from a thin line of drool leaking out. 

“God, what am I gonna do with you?” Atsumu muttered. Whether he knew it or not, Osamu was definitely testing his patience right now, especially since it’d been a bit since they last fooled around. They were both busy now that they were third years, and it was hard to find time when they were both free and in the mood. Osamu’s sleep schedule was a problem, too, since he slept significantly more than Atsumu and went to bed earlier as well. But, maybe—

Maybe that didn’t have to be an issue, Atsumu thought. Maybe he could make do like this. Osamu wouldn’t mind, right? Cautiously, he leaned forward and kissed his brother. He was slow and gentle at first as to not wake him up, but Osamu let out a tiny whine and Atsumu couldn’t hold himself back anymore. 

He crawled on top of him and pinned him to the couch, accidentally clashing their teeth together as he deepened the kiss, shoving his tongue down his twin’s mouth and rocking his hips, exhaustion suddenly gone. He didn’t realize how pent up he was. He could feel himself growing hard already, and he reached out to grope Osamu’s chest, squeezing before running his thumbs over his nipples, chuckling when he felt Osamu shiver underneath him. 

If he were awake, Osamu would definitely object. He always complained when Atsumu tried to toy with his chest, saying no at first until eventually caving; Atsumu always got what he wanted, and Osamu had always been bad at denying him. Besides, they both knew he  _ liked _ it when Atsumu played with his tits. They were extremely sensitive, and even now Atsumu could feel Osamu’s dick twitch and leak in his shorts. 

It was just that he was easily flustered, and nothing made him more embarrassed than how quickly Atsumu pinching his nipples got him hard, how easy it was to turn him into a desperate, panting mess. Watching his embarrassment was a joy, but this was nice, too. Atsumu could definitely appreciate uninterrupted time with Osamu’s tits.

He ducked his head down and wrapped his lips around one of Osamu’s nipples, pinching and squeezing the other one as he sucked gently. Osamu let out a sleepy moan, face scrunching up but eyes remaining shut. He’d always been a heavy sleeper. Atsumu smirked. 

He continued playing with Osamu’s tits until his brother was fully hard then pulled away, tugging Osamu’s shorts down as he sat back on his heels.

“Get these nice and wet, ‘kay?” He said even though Osamu couldn’t hear him. “The lube’s too far, ‘m too lazy to go get it.” He pried Osamu’s lips apart and shoved three fingers in, fucking them in and out of his mouth. He could feel the spit build up under Osamu’s tongue, and it dribbled out of the corners of his mouth as he gagged weakly around Atsumu’s fingers, which Atsumu pulled out after a minute or so.

“God, ‘Samu, yer so fuckin’ hot.” Atsumu said, pressing a spit-slick finger against Osamu’s hole before pushing it in slowly. Osamu didn’t even stir. Atsumu felt himself get harder. Something about this was so, so much hotter than he thought it’d be.

Slowly, he worked Osamu up from one finger to two, to three, and then four, which was probably unnecessary, but he didn’t care. Seeing Osamu stuffed full was endlessly sexy. He scissored his fingers and angled them against Osamu’s prostate. 

Osamu moaned, hips twitching and thighs trembling as Atsumu continued fingering him almost mercilessly. If he were awake, Osamu would be a whimpering mess, sobbing out incoherent begging and crying for Atsumu to fuck him. Now, though, he could only whine quietly, forced to take whatever Atsumu gave him. 

“Feel good?” Atsumu asked somewhat condescendingly, pleased to hear Osamu moan again. “God, yer such a slut. You look so pretty, baby, feel so tight around my fingers. Can’t wait to be inside ya, ‘Samu, yer so hot-”

He cut himself off with a groan when Osamu clenched around him, and he decided he couldn’t wait anymore. He pulled his fingers out. Osamu whined at the loss, and Atsumu chuckled. “Shh, don’t worry baby, I’ll fill ya up soon,” He mumbled, pressing a kiss to Osamu’s forehead. “I know what ya need.” Atsumu spit in his hand, slicked up his dick, and aligned himself with Osamu’s hole, thrusting in gently. He stilled for a moment once he was all the way in, not wanting to hurt Osamu, but he didn’t have enough patience to wait that long. 

After a few minutes, he started fucking Osamu in earnest, quickly picking up speed and moaning openly. Osamu stirred underneath him and, when Atsumu wrapped a hand around Osamu’s cock, his eyes blinked open, still bleary from sleep.

“Wh-” He tried to ask what was happening, but he was cut off by a loud, needy moan as Atsumu started jacking him off.  _ “Fuck-  _ Tsumu, please-” 

“Please what, baby? What do ya need?”

“I- I need-” Osamu struggled to speak, tears bubbling up in his eyes and drool running down his chin. Atsumu was fucking him hard and fast now, and it was hard to focus, moans and whines leaving him uncontrollably. “Need to cum-”

“Already?” Atsumu teased. He let go of Osamu’s cock, and Osamu cried in frustration. “I’ve barely done anything, ‘Samu. How much of a slut are ya?”

“I’m not-”

“Don’t deny it, not when yer moanin’ like a bitch in heat. Yer a whore, ‘Samu. I know you like this, I know you like when I talk down to you-”

Osamu shook his head. “No, I don’t-”

“Stop lying. Yer body’s betrayin’ ya, I can see how hard ya are, see how much ya like this, how much of a slut you are. Say you like it, ‘Samu,” Atsumu’s hips stilled completely, “Say it and I’ll let you cum.”

“I don’t like it,” Osamu continued to lie, weakly trying to rock his hips and fuck himself on his brother’s cock.

Atsumu laughed and held his hips still, smirking. “If you wanna cum, ya gotta tell me you like it.”

Osamu hesitated, but his resolve was quickly crumbled by desperation. “I-I like it,” He stuttered softly under his breath.

“Louder.”

“I like it!” Osamu cried, trying to wiggle his hips again. “Please, ‘Tsumu, I like it so much, let me cum, please-”

Atsumu started pounding into him again, and Osamu practically screamed, eyes squeezing shut as he moved in time with Atsumu’s thrusts, moaning loudly. Atsumu wrapped a hand around Osamu’s cock. “You can cum now, baby, go ahead.”

Osamu’s back arched and his toes curled as he came all over himself. He went slack against the couch after, panting and trying to catch his breath, but Atsumu didn’t relent. He kept fucking him at a brutal pace, even as Osamu started to sob from the overstimulation. 

“W-Wait, Tsumu, stop-” Osamu tried to object, squirming underneath Atsumu, who pinned him to the couch in response. “I can’t- I- Stop, I need to-”

Atsumu didn’t stop. He held Osamu down harder, still fucking him, like he was nothing but a toy to get himself off with. “What is it?”

Osamu grew embarrassed. “I need to piss,” He said, looking away and covering his face.

Atsumu paused. It made sense. Osamu had been asleep until now, and he always went to the bathroom first thing in the morning, much to Atsumu’s displeasure. He fell asleep by accident, too, so he probably didn’t go earlier.

Slowing down his thrusts, Atsumu weighed his options. “How bad?” He asked.

“Real bad,” Osamu squeaked, face bright red.

After a bit more thinking, Atsumu started fucking Osamu again, just as hard and fast as before. Osamu whimpered pitifully. “Sucks to be you then, ‘cause I ain’t stoppin’ till I get off.”

“T-Tsumu, please, I can’t-” Osamu gasped, writhing against the couch, his legs kicking uselessly. “I need to-” He started crying again. “I-I really need to-”

Atsumu smirked and pressed one of his hands down on Osamu’s bladder. “Then go.”

Osamu was mortified. His eyes widened, and he shook his head, moaning despite himself as Atsumu hit his prostate. “No-”

_ “Go, ‘Samu,”  _ Atsumu ordered, pressing his hand so hard it almost hurt. 

_ “Tsumu-” _ Osamu couldn’t control himself. His body relaxed against his will, and he felt humiliated as piss started leaking out of his dick, slowly at first but picking up speed, spilling all over his chest and the couch and trickling to the floor. A faint hissing sound filled the room as he emptied his bladder, and Atsumu kept fucking him the whole time, forcing moans out of his lips.

“What a whore,” Atsumu jeered, loving to tease Osamu. “Can’t control yerself, hm? Gross.”

Osamu sobbed. His dick twitched, though, which didn’t escape Atsumu’s notice. Atsumu started jacking him off again, for the third time.

“And yer gettin’ hard, too? I knew you were a slut, but this is ridiculous, ‘Samu. Don’t tell me ya actually  _ liked  _ that.”

“I-I didn-t-”

“Really? ‘Cause yer body’s tellin’ me somethin’ else. Do ya wanna get off again? Wanna cum twice after pissin’ yerself like a dog?”

Osamu shook his head, but it was obvious to Atsumu that he wanted to keep going. They’d fucked enough times and done enough gross shit for Atsumu to know when Osamu actually wanted to stop and when he was too embarrassed to say he wanted to keep going.

Atsumu picked up the pace one last time, jacking Osamu off. He’d been close for a while now so, as much as he wanted to tease, he knew he couldn’t draw this out much longer. When Osamu started trying to move his hips again, Atsumu couldn’t take it anymore. He came inside his brother with a low groan, and jacked him off until Osamu was staining his stomach white again, piss and cum mixing in a disgusting pile of bodily fluids.

When he pulled out, he watched his cum leak out of Osamu’s ass, captivated. God, Osamu was  _ wrecked.  _ His eyes were glossy and distant. He looked absolutely fucked out. Atsumu was tired, too, but he had an idea.

He stood up suddenly and put a hand on Osamu’s shoulder, pinning him against the couch’s arm rest.

“What’re you-”

Osamu was cut off by piss hitting his face and sloshing onto the floor. Atsumu was pissing on him, he realized, Atsumu was pissing on his  _ face. _ Forget earlier, this was definitely the most humiliated he felt in his life. It smelled awful and he tried to get away, but Atsumu kept him held down firmly, not letting go until he was finished and Osamu’s piss-soaked hair was matted to his forehead.

He sat on the couch next to Osamu and shut his eyes, catching his breath.

After a few minutes, when he seemed to come back to himself fully, Osamu sat up. “How the fuck are we gonna clean this up before mom and dad get back tomorrow?” He asked.

Atsumu shrugged. He didn’t think that far ahead, honestly. “... Buy a new couch?” He tried.

“What, and new carpeting too?” Osamu put his head in his hands, ignoring how wet it felt. “God, ‘Tsumu, I hate yer fuckin’ guts.”

“Really? Cause earlier-”

Before he could finish his sentence, Osamu shoved Atsumu off of the couch and onto the piss-covered floor.

**Author's Note:**

> Ahaha get it hah the fic is called letting sleeping dogs lie 'cause osamu pisses himself like a dog but is asleep at the beginning lol hahaha
> 
> I'll be the first to admit that I don't actually like watersports done this hard (I like omorashi for the humiliation aspect, but when there's too much piss I get worried about cleaning and turned off) but this was fun to write! Hope you like it!


End file.
